THIS IS A NEW SPECIFICATION

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1 TIS IS A NEW SPECIFICATION ADVANCED SUBSIDIARY GCE CEMISTRY A Chains, Energy and Resources F322 * OCE / * Candidates answer on the Question Paper OCR Supplied Materials: Data Sheet for Chemistry A (inserted) Other Materials Required: Scientific calculator Thursday 14 January 2010 Morning Duration: 1 hour 45 minutes * F * INSTRUCTIONS TO CANDIDATES Write your name clearly in capital letters, your Centre Number and Candidate Number in the boxes above. Use black ink. Pencil may be used for graphs and diagrams only. Read each question carefully and make sure that you know what you have to do before starting your answer. Answer all the questions. Do not write in the bar codes. Write your answer to each question in the space provided, however additional paper may be used if necessary. INFORMATION FOR CANDIDATES The number of marks is given in brackets [ ] at the end of each question or part question. Where you see this icon you will be awarded marks for the quality of written communication in your answer. This means for example you should: ensure that text is legible and that spelling, punctuation and grammar are accurate so that meaning is clear; organise information clearly and coherently, using specialist vocabulary when appropriate. You may use a scientific calculator. A copy of the Data Sheet for Chemistry A is provided as an insert with this question paper. You are advised to show all the steps in any calculations. The total number of marks for this paper is 100. This document consists of 20 pages. Any blank pages are indicated. OCR 2010 [/500/7834] DC (SJ/SW) 19234/3 OCR is an exempt Charity Turn over

2 2 Answer all the questions. 1 Kerosene is used as a fuel for aeroplane engines. (a) Kerosene is obtained from crude oil. Name the process used to obtain kerosene from crude oil and explain why the process works [2] (b) Some of the hydrocarbons in kerosene have the formula C (i) What is the name of the straight chain hydrocarbon with the formula C 10 22?... [1] (ii) Draw the skeletal formula of one branched chain isomer with the formula C [1] (iii) Explain why the straight chain isomer of C has a higher boiling point than any of its branched chain structural isomers.... [2] (iv) Explain why the straight chain isomer of C is converted by the petroleum industry into its branched chain isomers.... [1] OCR 2010

3 3 (c) When kerosene burns in an aeroplane engine very little carbon monoxide, CO, is formed but a significant amount of nitrogen monoxide, NO, is formed. (i) Construct the equation to show the complete combustion of C [2] (ii) Suggest, with the aid of an equation, how NO is formed within an aeroplane engine.... [1] (d) NO is a radical and contributes towards ozone depletion in the stratosphere. (i) What is a radical?... [1] (ii) One of the processes leading to the breakdown of ozone in the stratosphere can be represented by the following two equations. NO(g) + O 3 (g) NO 2 (g) + O(g) NO 2 (g) + O 2 (g) NO(g) + O 2 (g) What is the role of the NO in this process?... [1] (iii) Ozone in the stratosphere is broken down to make O 2 and O. Describe and explain how the concentration of ozone in the stratosphere is maintained.... [2] (iv) Why is it important to life on the Earth s surface that the concentration of ozone in the stratosphere is maintained?... [1] [Total: 15] OCR 2010 Turn over

4 2 Dilute aqueous hydrogen peroxide, 2 O 2 (aq), is used to sterilise contact lenses. 4 (a) Dilute 2 O 2 (aq) slowly decomposes at room temperature to produce oxygen and water. The decomposition of 2 O 2 (aq) can be made faster by: increasing the concentration of the 2 O 2 (aq), adding a small amount of manganese(iv) oxide catalyst, heating the solution to 60 C. (i) Construct the equation for the decomposition of 2 O [1] (ii) Explain why increasing the concentration of 2 O 2 (aq) increases the rate of decomposition.... [2] (iii) Explain how the catalyst can increase the rate of decomposition of 2 O 2 (aq).... [2] OCR 2010

5 (iv) 5 Explain why increasing the temperature of 2 O 2 (aq) increases the rate of decomposition. As part of your answer, you should add a second curve and any necessary labels to the Boltzmann distribution of molecular kinetic energies shown below. number of molecules with a given energy energy... [3] OCR 2010 Turn over

6 6 (b) (i) In the past, hydrogen peroxide was manufactured by reacting barium peroxide, BaO 2, with ice-cold dilute sulfuric acid. BaO 2 (s) + 2 SO 4 (aq) BaSO 4 (s) + 2 O 2 (aq) This method required the disposal of poisonous barium compounds. Calculate the atom economy for this manufacture of hydrogen peroxide from BaO 2. Use the table of relative formula masses given below. compound relative formula mass BaO SO BaSO O atom economy =... % [2] OCR 2010

7 (ii) 7 Nowadays, hydrogen peroxide is manufactured using hydrogen gas, oxygen from the air and a substance called anthraquinone. stage anthraquinone anthraquinol stage 2 O 2 + anthraquinol 2 O 2 + anthraquinone Compare the manufacture of 2 O 2 from hydrogen and oxygen with the manufacture from barium peroxide described in b(i). Explain the advantages of the manufacture of 2 O 2 from hydrogen and oxygen.... [3] (c) Some reactions of 2 O 2 are exothermic. Use ideas about the enthalpy changes that take place during bond breaking and bond making to explain why some reactions are exothermic [2] [Total: 15] OCR 2010 Turn over

8 3 Glucose, C 6 12 O 6, can be completely combusted to give carbon dioxide and water. 8 C 6 12 O 6 (s) + 6O 2 (g) 6CO 2 (g) O(l) (a) In the body, the conversion of glucose into carbon dioxide and water takes place in a number of stages catalysed by enzymes. What name is given to this oxidation process in the body?... [1] (b) A student carries out an experiment to determine the enthalpy change of combustion of glucose. In the experiment, g of glucose is burned. The energy released is used to heat 100 cm 3 of water from 23.7 C to 41.0 C. (i) Calculate the energy released, in kj, during combustion of g glucose. The specific heat capacity of water = 4.18 J g 1 K 1. Density of water = 1.00 g cm 3. energy =... kj [2] (ii) Calculate the amount, in moles, of glucose that is burned. amount =... mol [2] (iii) Calculate the enthalpy change of combustion of glucose. Give your answer to three significant figures. Δ c =... kj mol 1 [2] OCR 2010

9 9 (c) The standard enthalpy change of combustion of glucose can also be determined indirectly. Calculate the standard enthalpy change of combustion of glucose using the standard enthalpy changes of formation below. substance O Δ f / kj mol 1 C 6 12 O 6 (s) 1250 CO 2 (g) O(l) 286 C 6 12 O 6 (s) + 6O 2 (g) 6CO 2 (g) O(l) 1 answer =... kj mol 1 [3] (d) Suggest two reasons why standard enthalpy changes of combustion determined experimentally are less exothermic than the calculated theoretical values [2] [Total: 12] OCR 2010 Turn over

10 4 A reaction mechanism shows the individual steps that take place during a reaction. 10 (a) Methane reacts with bromine in the presence of ultraviolet radiation to form several products. Two of these products are bromomethane and hydrogen bromide. (i) Write an equation for the reaction between methane and bromine to make bromomethane and hydrogen bromide.... [1] (ii) Name one other bromine-containing organic product which is formed when methane reacts with bromine.... [1] (iii) The mechanism for this reaction is called radical substitution. Describe the mechanism for the radical substitution of methane by bromine to make bromomethane. Use the mechanism to suggest why a small amount of ethane is also formed. In your answer, you should organise your answer and use the correct technical terms.... [7] OCR 2010

11 11 (b) The curly arrows model is used in reaction mechanisms to show the movement of electron pairs during chemical reactions. Choose a reaction mechanism that you have studied involving the curly arrow model. Name and describe your chosen reaction mechanism. In your answer, include: an example of the reaction with the chosen mechanism, the type of bond fission that occurs, relevant dipoles [6] [Total: 15] OCR 2010 Turn over

12 12 5 Alkenes are a very useful series of hydrocarbons used widely in synthesis. Alkenes are more reactive than alkanes. (a) What is the name of the process used to convert long chain alkanes into more useful shorter chain alkenes?... [1] (b) Ethene and steam can be converted into ethanol. The equilibrium is shown below. C 2 4 (g) + 2 O(g) C 2 5 O(g) Δ = 46 kj mol 1 le Chatelier s principle can be used to predict the effect of changing conditions on the position of equilibrium. (i) Name the catalyst used in this reaction.... [1] (ii) State le Chatelier s principle.... [1] (iii) Using le Chatelier s principle, predict and explain the conditions that would give the maximum equilibrium yield of ethanol from ethene and steam.... [3] (iv) The actual conditions used are 60 atmospheres pressure at 300 C in the presence of a catalyst. Compare these conditions with your answer to (iii) and comment on why these conditions are used.... [3] OCR 2010

13 13 (c) Alkenes are used to make addition polymers. The repeat unit for an addition polymer is shown below. C C 3 C n What is the name of the monomer used to make this polymer?... [1] (d) Poly(chloroethene) has the repeat unit below. Cl C C n This repeat unit can be written as C 2 CCl. One way to dispose of poly(chloroethene) is to react it with oxygen at high temperature. This is called incineration. (i) Complete the following equation that shows the reaction taking place during incineration. C 2 CCl + O 2 CO O + Cl [1] (ii) Research chemists have reduced the environmental impact of incineration by removing the Cl formed from the waste gases. Suggest a type of reactant that could be used to remove the Cl.... [1] (e) The disposal of polymers causes environmental damage. Research chemists are developing polymers that will reduce this environmental damage and increase sustainability. Describe two ways in which chemists can reduce this environmental damage [2] OCR 2010 [Total: 14] Turn over

14 6 This question is about the six alcohols below. 14 butan-2-ol 2-methylpentan-3-ol propan-1-ol ethane-1,2-diol 2-methylpropan-2-ol propan-2-ol (a) Which alcohol is an example of a tertiary alcohol?... [1] (b) Draw the skeletal formula for 2-methylpentan-3-ol. [1] (c) Butan-2-ol and 2-methylpropan-2-ol are structural isomers. (i) What is meant by the term structural isomer?... [1] (ii) Draw another structural isomer of these two alcohols. [1] (d) Ethane-1,2-diol can be dissolved in water to act as an anti-freeze in car radiators. Explain why ethane-1,2-diol is very soluble in water [2] OCR 2010

15 15 (e) Ethane-1,2-diol is heated under reflux with ethanoic acid and a small amount of 2 SO 4 catalyst. Compound A is formed with molecular formula C 6 10 O 4. Draw the structure of compound A. [2] (f) Butan-2-ol is heated with 2 SO 4 catalyst. A mixture of three alkenes forms, B, C and D. The alkenes B and C are stereoisomers. (i) Draw the structures of the two stereoisomers B and C. [2] (ii) What type of stereoisomerism is shown by B and C?... [1] (iii) Draw the structure of the other alkene, D, that is formed in this reaction. [1] OCR 2010 Turn over

16 (g) Alcohol E is one of the following alcohols. 16 butan-2-ol 2-methylpentan-3-ol propan-1-ol ethane-1,2-diol 2-methylpropan-2-ol propan-2-ol A student oxidises alcohol E by heating under reflux with excess acidified potassium dichromate(vi). An organic product F is isolated. The mass spectrum of the alcohol E is shown below relative intensity m / z The infrared spectrum of the organic product F is shown below. 100 transmittance (%) wavenumber / cm OCR 2010

17 Name or draw the structures of the alcohol E and the organic product F. 17 Write an equation for the reaction of alcohol E with acidified potassium dichromate(vi). Use [O] to represent the oxidising agent, acidified potassium dichromate(vi). In your answer, you should make clear how each structure fits with the information given above [7] [Total: 19] OCR 2010 Turn over

18 18 7 There is much international concern that an increase in atmospheric concentrations of carbon dioxide and methane may lead to global warming and climate change. (a) Carbon dioxide and methane are both greenhouse gases. (i) What type of radiation is absorbed by methane molecules and what effect does this radiation have on these molecules?... [2] (ii) Some scientists are more concerned about carbon dioxide as a greenhouse gas than methane. Suggest why.... [1] (b) Describe ways that research chemists are trying to minimise climate change resulting from global warming caused by the release of greenhouse gases [5] OCR 2010

19 19 (c) Research scientists working in the Antarctic have measured the concentration of carbon dioxide in the ice. This study has allowed the scientists to estimate the atmospheric concentration of carbon dioxide over many thousands of years. The graphs below show these atmospheric concentrations and the corresponding average surface temperature CO 2 / ppm change in temperature / C age (thousands of years before present) present day temperature age (thousands of years before present) Do the graphs provide reliable evidence that an increase in atmospheric carbon dioxide concentration will result in global warming? Explain your answer [2] OCR 2010 END OF QUESTION PAPER [Total: 10]

20 20 PLEASE DO NOT WRITE ON TIS PAGE Copyright Information OCR is committed to seeking permission to reproduce all third-party content that it uses in its assessment materials. OCR has attempted to identify and contact all copyright holders whose work is used in this paper. To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced in the OCR Copyright Acknowledgements Booklet. This is produced for each series of examinations, is given to all schools that receive assessment material and is freely available to download from our public website ( after the live examination series. If OCR has unwittingly failed to correctly acknowledge or clear any third-party content in this assessment material, OCR will be happy to correct its mistake at the earliest possible opportunity. For queries or further information please contact the Copyright Team, First Floor, 9 ills Road, Cambridge CB2 1GE. OCR is part of the Cambridge Assessment Group; Cambridge Assessment is the brand name of University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge. OCR 2010

21 F322 Mark Scheme January 2010 F322 Chains, Energy and Resources Question Expected Answers Marks Additional Guidance 1 (a) 2 Fractional distillation DO NOT ALLOW just distillation Because fractions have different boiling points For fractions, ALLOW components OR hydrocarbons OR compounds ALLOW condense at different temperatures ALLOW because van der Waals forces differ between molecules IGNORE reference to melting points IGNORE crude oil OR mixture has different boiling points but ALLOW separates crude oil by boiling points (b) (i) Decane 1 DO NOT ALLOW deceane (ii) Skeletal formula of branched C Formula must be skeletal AND must not include any symbol, e.g. C 3 Any possible skeletal formulae e.g. 13

22 F322 Mark Scheme January 2010 Question Expected Answers Marks Additional Guidance (iii) (iv) Decane has more surface contact OR branched chains have less surface contact Decane has more van der Waals forces OR branched chains have fewer van der Waals forces Branched chains have more efficient combustion OR decane has less efficient combustion 2 Both answers need to be comparisons Assume it refers to decane IGNORE surface area ALLOW straight chains can get closer together OR branched chains cannot get as close to one another IGNORE branched chain are more compact ALLOW Decane has stronger van der Waals forces OR branched chains have weaker van der Waals forces More intermolecular forces is not sufficient 1 ALLOW branched chains are easier to burn OR easier to combust OR burn better OR more efficient fuel OR less likely to produce pre-ignition or knocking OR increases octane rating ALLOW ORA for decane 14

23 F322 Mark Scheme January 2010 Question Expected Answers Marks Additional Guidance Better fuel is NOT sufficient Burns more cleanly is NOT sufficient (c) (i) C ½O 2 10CO O 2 ALLOW any correct multiple IGNORE state symbols All four species correct balancing of four correct species (ii) N 2 + O 2 2NO 1 ALLOW any correct multiple including fractions IGNORE state symbols The mark is for the equation IGNORE writing 15

24 F322 Mark Scheme January 2010 Question Expected Answers Marks Additional Guidance (d) (i) Species with an unpaired electron 1 ALLOW atom, molecule or particle with an unpaired electron ALLOW has an unpaired electron ALLOW particle formed by homolytic fission (ii) catalyst 1 DO NOT ALLOW particle with a single electron OR particle with a free electron (iii) O + O 2 O 3 OR O reacts with O 2 to make ozone OR the reaction is reversible Rate of formation of ozone is the same as rate of decomposition 2 ALLOW O 2 + O O 3 OR O 3 O 2 + O ALLOW is in equilibrium OR in correct equation OR has steady state condition IGNORE other equations involving ozone (iv) absorbs (harmful) UV 1 ALLOW keeps out UV OR filters UV ALLOW increased UV could cause skin cancer OR increased UV could cause cataracts OR increased UV could cause mutation of crops Total 15 IGNORE gamma 16

25 F322 Mark Scheme January 2010 Question Expected Answers Marks Additional Guidance 2 (a) (i) 2 2 O O + O 2 1 ALLOW any correct multiple including fractions IGNORE state symbols (ii) (iii) More crowded particles OR more particles per (unit) volume more collisions per second OR more frequent collisions Any two from the following: Reaction takes alternative route Activation energy is lowered More molecules have energy above activation energy OR more molecules have enough energy to react 2 ALLOW particles are closer together DO NOT ALLOW area instead of volume IGNORE more concentrated particles 2 ALLOW collisions more often OR increased rate of collision OR collisions are more likely OR there is a greater chance of collisions More collisions is not sufficient ALLOW catalyst changes reaction mechanism ALLOW an alternative approach using adsorption particles adsorbed onto surface so bonds weakened as a result of the adsorption 17

26 F322 Mark Scheme January 2010 Question Expected Answers Marks Additional Guidance (iv) Correct curve for higher temperature 3 maximum of curve to right AND lower than maximum of original curve AND above dotted line at higher energy as shown in diagram below Activation energy does not change OR clearly labelled on diagram, e.g. E a OR E IGNORE minor point of inflexion of curve Note that the diagram above would score all 3 marks More molecules have energy above activation energy OR more molecules have enough energy to react (b) (i) % More successful collisions is not sufficient 2 First mark for OR ( ) OR ( ) at bottom of fraction with or without 100 ALLOW from 2 sig figs up to calculator value ALLOW full marks for 13 OR 12.7 OR OR up to calculator value with no working out scores one mark only NO ECF for this part from incorrect numbers in first expression 18

27 F322 Mark Scheme January 2010 Question Expected Answers Marks Additional Guidance (ii) Any three from the following: 3 Oxygen comes from air No poisonous materials formed OR no poisonous materials involved No waste products formed OR atom economy is 100% IGNORE hydrogen comes from the air IGNORE harmful ALLOW higher atom economy Anthraquinone is regenerated OR recycled OR used again OR Anthraquinone acts as a catalyst (c) Bond breaking absorbs energy AND bond making releases energy More energy released than absorbed 2 ALLOW bond breaking is endothermic AND bond making is exothermic ALLOW exothermic change transfers more energy than endothermic change OR bond making transfers more energy than bond breaking OR (the sum of the) bond enthalpies in the products is greater than the (sum of the) bond enthalpies in the reactants OR (the sum of the) bond enthalpies of the bonds made is greater than (the sum of) the bond enthalpies of the bonds broken IGNORE reference to strong and weak bonds IGNORE enthalpy of products is less than enthalpy of reactants Total 15 19

28 F322 Mark Scheme January 2010 Question Expected Answers Marks Additional Guidance 3 (a) Respiration 1 IGNORE anaerobic (b) (i) (kj) 2 ALLOW 7231 J ALLOW 7.23 with no working out ALLOW from 7.2 up to calculator value of ALLOW from up to calculator value for 1 mark (i.e. ECF from use of m = in first stage) IGNORE sign (ii) M r = (iii) amount = (mol) c = 1560 (kj) OR 1570 (kj) but answer must be to 3 sig fig minus sign ALLOW OR OR up to calculator value DO NOT ALLOW ALLOW ECF from wrong M r 2 ALLOW ECF from answer to (i) answer to (ii) but answer must be to 3 sig fig minus mark is an independent mark 20

29 F322 Mark Scheme January 2010 Question Expected Answers Marks Additional Guidance (c) ALLOW full marks for 2830 with no working out +( 394 6) + ( 286 6) OR ALLOW for 2 marks: cycle wrong way around OR 1400 OR 860 one value not 6 OR 5330 OR wrong sign for 1250 or 4080 OR +570 correct cycle but not 6 ALLOW for 1 mark: 1400 OR 860 cycle wrong way around and one value not 6 OR 570 cycle wrong way around and not 6 OR 1930 OR wrong sign and not 6 Note: There may be other possibilities. (d) Any two from the following: 2 eat released to the surroundings Incomplete combustion OR incomplete reaction OR not everything burns ALLOW heat loss IGNORE reference to evaporation Non-standard conditions Total 12 21

30 F322 Mark Scheme January 2010 Question Expected Answers Marks Additional Guidance 4 (a) (i) C 4 + Br 2 C 3 Br + Br 1 ALLOW any correct multiple IGNORE state symbols (ii) Dibromomethane OR tribromomethane OR tetrabromomethane 1 ALLOW 1,1-dibromomethane OR 1,1,1-tribromomethane etc ALLOW 1-dibromomethane DO NOT ALLOW 2,2-dibromomethane etc (iii) Br 2 2Br OR homolytic fission of bromine Br + C 4 Br + C 3 C 3 + Br 2 C 3 Br + Br Br + C 3 C 3 Br OR Br + Br Br 2 Ethane made when two methyl radicals react OR C 3 + C 3 C 2 6 Quality of Written Communication Consists of initiation step linked to correct equation propagation step linked to one equation in which there is a radical on the left and a radical on the right termination step linked to correct equation: 2 names of steps linked to correct equations BUT 3 names of steps linked to correct equations ALLOW correct formulae e.g. C 2 Br 2 7 All equations can be described in words Radicals do NOT need a single dot IGNORE any state symbols ALLOW any other suitable termination If no equations are given to link the names of the step then award one mark for mention of all three steps 22

31 F322 Mark Scheme January 2010 Question Expected Answers Marks Additional Guidance (b) EITER Nucleophilic substitution Example of nucleophilic substitution eterolytic fission C I curly arrow Correct dipole on C I bond O curly arrow from one lone pair on O of O ion OR from minus sign on O ion 6 The example mark can be awarded as an example of the name of the mechanism given or if the name is wrong can be given as an example of a reasonably correct drawn mechanism If curly half arrows drawn do not give a mark the first time used and then apply ECF 3 C C I 3 C C O + I O OR Electrophilic addition Example of electrophilic addition eterolytic fission Curly arrow from C=C bond to Br Br bond and Dipole and curly arrow associated with Br 2 Correct carbocation ion Curly arrow from one lone pair on Br ion OR from minus sign on Br ion ALLOW Electrophilic substitution Example of electrophilic substitution eterolytic fission Curly arrow from benzene ring to the electrophile (i.e. NO 2 + OR Br + ) Correct intermediate Curly arrow to show loss of hydrogen ion ALLOW mechanisms for other halogenoalkaes C 3 C C Br Br C 3 C Br Br C C 3 C 3 ALLOW mechanisms for other halogens and hydrogen halides ALLOW Nucleophilic addition Example of nucleophilic addition eterolytic fission Correct dipole on carbonyl group Curly arrow from lone pair on ion OR from minus sign on to C=O carbon and breaking of C=O bond Curly arrow from carbonyl oxygen to either + or 2 O Total 15 23

32 F322 Mark Scheme January 2010 Question Expected Answers Marks Additional Guidance 5 (a) Cracking 1 ALLOW catalytic or thermal cracking (b) (i) Acid 1 ALLOW correct formula if no name given: e.g. 3 PO 4 OR 2 SO 4 OR + ALLOW correct name of acid even if an incorrect formula is used (ii) (iii) (iv) The position of equilibrium will shift so as to minimise the effect of any change in conditions Low temperature AND high pressure Low temperature because the (forward) reaction is exothermic igh pressure because there are fewer moles (of gas) on the right hand side (60 atmosphere pressure is a) high pressure may be too expensive OR may cause safety problems (300 ºC is sufficiently high) to give a fast rate of reaction without shifting equilibrium to the left OR compromising equilibrium yield IGNORE heterogeneous OR homogeneous 1 DO NOT ALLOW reaction shifts The idea of a shift in equilibrium is essential 3 One mark for conditions. This mark is independent of the reasons for conditions 3 One mark for reason for the chosen temperature One mark for reason for the chosen pressure ALLOW fewer moles of products (c) Propene 1 ALLOW prop-1-ene DO NOT ALLOW prop-2-ene (d) (i) C 2 CCl + 2½O 2 2CO O + Cl 1 (ii) Alkali OR base OR carbonate 1 ALLOW correct formula of or named carbonate OR alkali OR base Correct name and wrong formula does not score 24

33 F322 Mark Scheme January 2010 Question Expected Answers Marks Additional Guidance (e) Any two marks from the following: 2 Develop photodegradable polymers Develop biodegradable polymers OR develop compostable polymers Develop techniques for cracking polymers OR develop use as a chemical feedstock Develop ways of making polymers from plant-based substances OR reduce the need to use finite raw materials such as crude oil Designing processes with high atom economy OR reduce waste products during manufacture Develop ways of sorting AND recycling polymers Total 14 25

34 F322 Mark Scheme January 2010 Question Expected Answers Marks Additional Guidance 6 (a) (i) 2-Methylpropan-2-ol 1 ALLOW methylpropan-2-ol (b) 1 Formula must be skeletal AND not include any symbol except for O O (c) (i) Same molecular formula but different structural formulae 1 ALLOW Same molecular formula but different arrangement of atoms OR Same molecular formula but different structures OR Same molecular formula but different displayed formulae DO NOT ALLOW Same molecular formula but different spatial arrangement of atoms (ii) C 3 C 2 C 2 C 2 O OR (C 3 ) 2 CC 2 O 1 ALLOW displayed formula ALLOW ALLOW sticks (i.e. no shown bonded to C) O OR O ALLOW DO NOT ALLOW O shown as below C C C C O C C C C O sticks OK and O is OK sticks OK but O is not OK ALLOW correct ethers 26

35 F322 Mark Scheme January 2010 Question Expected Answers Marks Additional Guidance (d) as O (bonds) OR has hydroxyl (groups) OR has hydroxy (groups) 2 ALLOW marks from a diagram of hydrogen bonding IGNORE reference to alcohol functional group Forms hydrogen bonds with water (molecules) (e) C 3 COOC 2 C 2 OOCC 3 1 mark for each ester end of molecule DO NOT ALLOW forms hydrogen bonds 2 ALLOW displayed formula OR skeletal formula ALLOW sticks C 3 COOC 2 C 2 O shows one of the two ester groups and scores one mark (f) (i) C 3 C 3 C 3 2 DO NOT ALLOW C C C C 3 C C 3 3 C O C 3 C C C C i.e. no ECF O C 3 (ii) E/Z 1 ALLOW cis-trans IGNORE geometric (iii) C 3 C 2 C=C 2 OR but-1-ene 1 If but-1-ene given in part (i), ALLOW but-2-ene OR C 3 C=CC 3 i.e. ECF from f(i) DO NOT ALLOW methylpropene: 3 C C C 3 C 27

36 F322 Mark Scheme January 2010 Question Expected Answers Marks Additional Guidance From the evidence, candidates may have identified compound F as propanone, propanal or propanoic acid The mark scheme for F = propanone and propanal is shown in the Expected Answers column. The mark scheme for F = propanoic acid is shown in the Additional Guidance column. If F is propanone or propanoic acid, then maximum score = 7; but if F is propanal then maximum score = 6 (g) Mark scheme for F = propanone and propanal 7 Mark scheme for F = propanoic acid mass spec of E Remember to check the spectrum Quality of Written Communication mass spec gives M + or molecular ion of 60 OR mass spec gives parent ion of 60 OR highest m/z (ALLOW m/e) value is 60 mass spec of E Remember to check the spectrum QWC mass spec gives M + or molecular ion of 60 OR mass spec gives parent ion of 60 OR highest m/z (OR m/e) value is 60 m/z = 45 indicates loss of C 3 OR m/z = 45 indicates presence of C 3 CO OR C 2 C 2 O OR C 2 5 O IR of F Remember to check the spectrum IR shows no broad absorption between 2500 to 3300 cm 1 so no O bond OR no broad absorption between 2500 to 3300 cm 1 so not a carboxylic acid IR shows absorption at 1700 cm 1 due to a C=O bond OR absorption at 1700 cm 1 indicates a ketone OR aldehyde present Identification and equation F is C 3 COC 3 OR propanone E is C 3 COC 3 OR propan-2-ol C 3 COC 3 + [O] C 3 COC O If F has been incorrectly identified as propanal, mark identification and equation as ECF, so max = 2 ALLOW E is C 3 C 2 C 2 O m/z = 45 indicates loss of C 3 OR m/z = 45 indicates presence of C 3 CO OR C 2 C 2 O OR C 2 5 O IR of F Remember to check the spectrum IR shows (broad) absorption somewhere between 3500 and 2500 cm 1 suggests carboxylic acid OR O bond IR shows absorption at 1700 cm 1 due to C=O OR absorption at 1700 cm 1 indicates a carboxylic acid Identification and equation F is C 3 C 2 COO OR propanoic acid E is C 3 C 2 C 2 O OR propan-1-ol C 3 C 2 C 2 O + 2[O] C 3 C 2 COO + 2 O ALLOW: C 3 C 2 C 2 O + [O] C 3 C 2 CO + 2 O Total 19 28

37 F322 Mark Scheme January 2010 Extra guidance for marking of Q6(g) If E has not been identified OR if F has been identified as a ketone or aldehyde, use the left-hand mark scheme If F has been identified as a carboxylic acid, use the right-hand mark scheme Mass spec These two marking points stand as independent marks whichever compounds have been identified. The positive sign for fragment ions is not required. IGNORE negative charge. The mass spec may well be on the actual spectrum. IR mark These stand as independent marks whichever compounds have been identified. The IR analysis may well be on the actual spectrum. Identification marks If both structure and name are given they must both be correct but allow propanol drawn with the correct structure because the position number of the O has been clearly identified ALLOW ECF for identification of F e.g. if E is pentan-2-ol then an answer of pentan-2-one for F will be given a mark as ECF ALLOW identification marks for E and F from equation Equation mark ALLOW ECF for any correct equation showing the oxidation of any alcohol to the appropriate product. ALLOW molecular formulae in equations, i.e. C 3 7 O + [O] C 2 5 CO + 2 O ; C 3 8 O + [O] C 3 6 O + 2 O ; C 3 7 O + [O] C 2 5 CO + 2 O 29

38 F322 Mark Scheme January 2010 Question Expected Answers Marks Additional Guidance 7 (a) (i) 2 Infrared (radiation absorbed) ALLOW bond stretching OR bond bending (ii) by (C ) bond vibration Greater concentration of carbon dioxide OR more carbon dioxide is being made DO NOT ALLOW molecules vibrating 1 ALLOW carbon dioxide is the main contributor to global warming DO NOT ALLOW any response that states that CO 2 causes ozone depletion ALLOW C=O bonds absorb IR more readily than C bonds ALLOW carbon dioxide has a greater greenhouse effect 30

39 F322 Mark Scheme January 2010 Question Expected Answers Marks Additional Guidance 7 (b) Any five from the following: Developing carbon capture AND storage 5 carbon, capture AND storage required ALLOW CCS One example of CCS Second example of CCS Examples of CCS deep in the oceans OR on the sea-bed DO NOT ALLOW dissolve CO 2 in the sea OR stored in ocean storage in geological formations OR piped into disused or partially filled oil wells or porous rocks OR under the sea-bed Provide evidence to governments OR international conferences (e.g. Kyoto) OR reports to United Nations etc Educating society OR writing in journals OR producing documentaries OR writing books OR making posters by reaction with metal oxides OR reaction to form (solid) carbonates OR stored as a carbonate OR equation to show formation of metal carbonate IGNORE mineral storage Monitoring atmospheric changes Develop alternative energy sources One example of an alternative energy source e.g. develop fuel cells OR developing solar power OR fuels that do not produce CO 2 (Develop) more efficient engines for transport OR lean burn engines OR hybrid engines OR electric cars Find uses for carbon dioxide OR named use: e.g. dry cleaning OR making decaffeinated coffee OR blowing agent OR fizzy drinks, etc ALLOW idea of biofuels only if linked to carbon-neutrality IGNORE reforestation IGNORE reference to CFCs DO NOT ALLOW use less carbon dioxide 31

40 F322 Mark Scheme January 2010 Question Expected Answers Marks Additional Guidance (c) Any two from the following: 2 There are times when CO 2 has a high concentration and the temperature is also high OR There are times when CO 2 has a low concentration and the temperature is low It is impossible to measure with certainty the average temperature years ago ALLOW a (positive) correlation between temperature and carbon dioxide concentration but DO NOT ALLOW just a correlation IGNORE graphs are the same shape IGNORE graphs are similar There are other gases that may cause a greenhouse effect OR There are other factors that may cause a greenhouse effect There are very few anomalous results Total 10 32